In Swahili (the lingua franca of East Africa): someone who wanders without purpose / someone constantly on the move.
It came to be applied to all white people in East Africa, as most were encountered as traders, visiting colonial officials or tourists.
Today, white tourists are often greeted (especially by children) with the cry: "Bye bye mzungu!"
For some reason, they rarely say "Hello mzungu!" when they see one coming...

Muzungu is a word from the languages of Kinyarwanda and Kirundi meaning "white person" (pl. 'bazungu'). It is closely related to the Kiswahili word 'mzungu', with which it is often confused by Westerners. A derivative is the derogatory 'kazungu' meaning 'little white person'.

Mzungu--- swahili word for white person, but not restricted to men only. Also used for European, caucasian women.
The word is commonly used by locals and not in a negative way (ie: it is viewed as complimentary to be Mzungu).

That Mzungu girl is so nice with her fair skin, blonde hair and blue eyes.